The process of transferring personnel from one vessel to an offshore installation or another vessel while both are at sea is a difficult and dangerous aspect of offshore platform work, particularly where rough seas or high wind conditions are present. Existing methods of achieving transfer have significant limitations in terms of safety and practicality. This invention offers a system which reduces the risks associated with transfer in a range of weather conditions.
In this field it is already known that there are several methods of transfer, which include those outlined below.
Most offshore transfers involve the use of a crane to lift and move the apparatus that carries personnel and equipment from an offshore platform or a vessel to another vessel, or vice versa.
Currently, a widespread apparatus to accomplish such a transfer is a rope basket having a rigid bottom, commonly known in the industry as a “Billy Pugh” basket. Personnel stand on the rigid bottom and hold onto the rope lines for support and safety. This apparatus has several major drawbacks. First, personnel are not typically secured to the basket. Second, personnel are not protected in any way from impact during the transfer. Third, additional space to transfer equipment is minimal. Finally, there is minimal provision to protect personnel and equipment in the event of submersion of the basket
Another structure for transferring personnel and equipment is described in U.S. Pat. No. 5,713,710. This patent discloses an apparatus for transferring objects from a first location to a second location. This transfer is accomplished through the use of a lifting device and a transfer device. The transfer device comprises an outer structure which defines an inner space in which an object to be transferred may be located and a securing device to secure the object to the transfer device during transfer. The transfer device of Strong is buoyant and self-righting when in water. The transfer device disclosed in Strong may include shock absorbing means on the underside.
In an intent to improve the structure described in U.S. Pat. No. 5,713,710, US patent application number 2001/0018015 A1 describes another structure capable of being attached to a lifting device such as a crane hook and comprising a load bearing support structure which supports a base and walled surface over a large surface area. A central support member for personnel is attached to a point on the base of the apparatus and a point on the top portion of the apparatus to provide stable support for a seating assembly and includes a dynamic compression system for supporting and distributing various weights. The load bearing central support structure is designed to create multiple pressure and stress points, thereby decreasing the force exerted at each point.
Although the apparatus described in U.S. Pat. No. 5,713,710 and US patent application number 2001/0018015 A1 are satisfactory in many respects, it has now been found that there is still room for improving the level of protection for the personnel during ingress to, transport and egress from said structures.